Printing ink



Patented Aug. 13, 1929.

UNITED STATES PATENT QFFICE.

GEORGE n. KNIGHT, on Rnnwoon CITY, CALIFORNIA, ASSIGNOR T0 EMORY WINSHIP, or MACON, GEORGIA.

PRINTING INK.

No Drawing.

The present invention relates to printing inks, and more particularly to that class of inks known as intaglio inks or inks adapted for printing etchings or engravings. 1

It is the practice in the art of printing etchings, engraving, and work of like character, such for example as theproduction of high grade prints, reproductions of pamtings, and the like, and in the printing of the picture sections of newspapers; to form the design, picture, or matter to be printed in copper or metallic surfaced plates or rolls by means of a series of depressions or recesses of varying depths. The smooth surface of the engraved or etched plate or roll represents the white or uncovered portion of the printed matter, and the depressions represent the colors or tones; the nature of the color or tone being dependent upon the depth of de pression from the surface ,of the plate or roll at each point. To effect printing, the depressions are filled with ink in any suitable manner, the excess ink is wiped from the surface of the roll or plate and the inked plate or roll is then brought into engagement with the surface upon which the impression is to be made. In the usual form of printing press for newspaper work, it is the practice to ink the rolls by causing a portion of the circumference thereof to contact with an ink supply as the rolls rotate. Just before the inked sections of the roll engage the surface upon which the imprint is to be made a w1ping member, commonly termed the doctor blade, engages the surface of the roll to w1pe the excess ink therefrom. For high grade prints, the rolls or plates are usually inked by means of suitable inking rollers or devices which are supplied with the ink from suitable fountains or reservoirs.

To be suitable for work of this character, inks must be of such a nature that they will readily spread or flow over the plate and from the doctor blade, must wipe readily from the surface of the roll or plate to leave What is known as a good wipe. It must also have sufficient adhesiveness to be retained in the depressions of the rolls or plates until brought into contact with the paper, and must have sufficient cohesion to pull out freely from the depression in the plate and transfer readily to the material upon which the imprint is to be'made; and the constituents of the inks must not set up injurious reactions with metal of the plates Application filed April 7,

orrolls. For successful high speed printing 1t is also essential that the ink shall dry with sufiiclent rapidity to avoid setting off on the bars of the folder in newspaper presses, or upon contiguous sheets of stacked freshly prlnted material. A satisfactory ink must also have the proper penetrative properties to rapldly draw or set the ink into the paper a reasonable depth and it .must have the necessary cohesion to prevent the ink from spreading laterally, or what is commonly termed bleeding.

Various inks for intaglio printing have been proposed, some of which are in common use. Inks of this type are ordinarily sold 1n paste form and are of such consistency that before use it is necessary to add a diluent thereto which is miscible with the ink composition and Which volatilizes readily or is converted into a gaseous form at low temperatures, enhacing the drying properties of the ink. Because of the nature of such compositions, hydro-carbon solvents or thinners such as gasoline, benzene, naptha and the like must be used. Because of the slow drying qualities of such inks it is necessary to apply relatively high heat to the freshly printed matter to cause rapid evaporation of the volatile constituents of the ink. The fumes emitted are toxic and nauseating in effect and constitute a nuisance in the vicinity of the press rooms unless elaborate and expensive measures are taken to dispose of them. The evolved gases and vapors are also highly inflammable having a low flash point, with the result that the fire hazards and insurance rates are very high. A further disadvantage of such prior inks is that they are of such a nature as to necessitate the use of hydro-carbon solvents ,to effect a proper cleaning of the printing presses. Because of the prohibitive cost of non-inflammable solvents, it is the practice to use the lower priced substances such as gasoline for cleaning purposes which add to the fire hazard, nuisance and injurious effects of these inks.

I have found it possible to provide improved carriers or vehicles for inks cone taining large percentages of 'water, which when used as vehicles or carriers for inks, reduce the inflammability and nauseating or toxic effects of the fumes emitted, and the fire hazard to a marked degree. At the same time the appearance, working and printing qualities of such inks are excellent in character. In this way I have been successful in producing high. grade inks at low cost, which are substantially non-injurious in character, liberate substantially no nauseating fumes when exposed to the atmosphere, are of low flammability; and with which an aqueous medium, including water, milk, skim milk and the like may be utilized as a diluent. Completed prints and impressions made by the preferred forms of my imroved inks are insoluble in water to such an extent that the effect of moisture thereon is of a high grade character. Such inks are what I term water inks.

Accordingly an object of the present invention is to provide inks which are relatively non-injurious and of low infiammability, are capable of withstanding the action of the elements to a degree suitable for use in high grade printing work, and dry with greater rapidity than inks heretofore proposed thereby permitting increased speed of operation of existing apparatus, and a corresponding reduction in labor and cost of operation in printing establishments.

A further object of the invention is the production of improved inks, in which an aqueous medium such as water, milk, skim milk or the like may be used as a diluent, and which after being imprinted on the material are substantially insoluble in water, and at the same time give a high grade finished and durable print, of good appearance and improved detail.

A still further object of the invention is to provide inks that will permit the incorporation of diluents therein without impairing the desired properties of the ink, and which will retain the pigment and solids incorporated therein in suspension upon the addition of diluents thereto.

Still further objects of the invention will appear from the more detailed description of the preferred embodiments hereinafter more fully set forth.

In carrying my invention into practical effect I employ as a vehicle or carrier for printing inks adapted for printing etchings or engravings one which includes an aqueous medium base as for example, milk, skim milk, or water and the like in which is suspended, dissolved, or chemically combined therewith a tacky gummy substance such as J casein, and a substance having. an alkaline reaction and adapted to assist or abet the suspension or dissolution of the casein in such medium such as borax. By way of example an ink of this type may be compounded in the following manner. To about 1,000 cc. of skim milk is added casein in the amount of about 5 to 150 grams, preferably about 85 grams. The casein is stirred into the milk and to this mixture of milk and casein is added from about 1 to 100 grams, preferably about 60 grams of borax or other alkaline substance in accordance with the quantity of casein used. The mixture is then agitated until the casein is colloidally suspended or apparently colloidally suspended in the milk; To this suspension is then addeda small percentage of formaldehyde, preferably about 4 drops, about 10 cc. of a 10 percent solution of carbolic acid, about 5 cc. of oil of citronella, and from 10 to 100, preferably 50 cc. of glycerin, in the order named, and while the mixture is under constant agitation. The proper pigments or coloring matters are then added, and the mixture is milled to form a colloidal suspension of the pigment and is then ready for use. This vehicle or carrier containing essentially skim milk, should contain approximately 73 to 97 percent of skim milk, about .09 to 7 percent of borax, about .4 to 11 percent of casein, about .7 to .9 percent of carbolic acid, about .35 to .4 percent of oil of citronella, about .9 to 7 percent of glycerin, and a trace of formaldehyde. Preferably such composition should comprise about 82 percent of skim milk, about 5 percent of borax, about 7 percent of casein, about .8 percent of carbolic acid, about .4 percent of oil of citronella, about 4: percent of glycerin, and a trace of formaldehyde.

Other ink compositions which my experiments demonstrated satisfy the requirements of the type of inks known as the water inks for intaglio and like printing, may be prepared in the following manner. To about 750 cc. of either skim milk or water, preferably water, Which has been heated to a temperature approximating the boiling point or a temperature of about 80 C. is added casein in the amount of about 10 to 75 grams, preferably 40 grams. The casein is stirred into the water, and to this casein water mixture is added about 20 to 7 5 grams, preferably 40 grams of borax. The mixture is then agitated until the casein is colloidally suspended or dissolved in the aqueous medium or water. To the mixture thus formed is then added the proper coloring material as lake or earth colors or pigments and the mass is thoroughly agitated until the coloring material has been taken up or has been apparently colloidally suspended therein, whereupon a polyhydric alcohol such as glycerin in the amount of about 1 to 150 cc. preferably 35 cc. is added thereto and the mass agitated until an emulsion or an apparent emulsion is formed. It has been found that glycerin gives body to the vehicle without interfering with the free flowing quality so essential in an ink of this type. Moreover, it prevents bubbling in the fountain and gives the prints a better finish. To enhance the preservative the ink compositions it is hig 1y desirable to incorporate therein about 1 to 35 cc., preferably 15 cc. of a 10% solution of carbolic roperties of utilized is skim milk, the amount of casein should be reduced, the limits being 20 to 75 grams, and the preferred amount being 55 grams. The ink composition containing water as the aqueous medium should contain approximately '67 to 95 percent of water, approximately 2.5 to 7 percent of casein, approximately 2.5 to 7 percent of borax, approximately any amount up to 13 percent of glycerin, approximately any,

amount up to 3 percent of carbolic acid, and approximately any amount up to 3 percent of oil of citronella. Preferably such com position should comprise about 83 percent of Water, about 6 percent of casein, about 4 percent of borax, about 4 percent of glycerin, about 2 percent of carbolic acid, and about. .7 percent of oil of citronella.

In the case wherein the ink compositlon includes skim milk as the aqueous medium, the relative limits of percentages of each ingredient forming a part of such composi tion should include approximately 67 to 96 percent of skim milk, approximately 1 to 7 percent of casein, approximately 2 to 7 percent of borax, approximately any amount up to 13 percent of glycerin, approximately any amount up to 3 percent of carbolic acid, and approximately any amount up to 3 percent of oil of citronella. .Preferably such compositions comprise about 84 percent of skim milk, about 4 percent of casein, about 4 percent of borax, about 4 percent of glycerin, about 2 percent of carbolic acid, and about .8 percent of oil of citronella.

Accordingly, having described the preferred embodiments of my invention, what is desired to be secured by Letters Patent and claimed as new is:

1. A printing ink composition comprising an aqueous medium, casein, borax, carbolic acid, oil of citronella and glycerin.

2. A printing ink composition comprising an aqueous medium, casein, borax, carbolic acid, oil of citronella, glycerin and formal dehyde.

3. A printing ink composition comprising an aqueous medium, casein, borax, carbolic acid, oil of citronella, glycerin, formaldehyde, and a coloring matter.

4. A printing ink composition comprising an aqueous medium, casein, borax, carbolic acid,'oi1 of citronella, and formaldehyde.

5. A printing ink composition comprising an aqueous medium, casein, borax, carbolic acid, oil of citronella, formaldehyde and a coloring matter.

6. A printing ink composition comprising skim milk, casein, borax, carbolic acid, oil of citronella, glycerin, and a coloring matter.

7. A printing ink composition comprising approximately 84 percent of an aueous medium, approximately 4 percent of casein, ap- I proximately 4 percent of borax, approximately four percent of glycerine, approxi mately 2 percent of carbolic acid and approximately .8 percent of oil of citronella.

8. A printing ink composition for use in intaglio printing comprising an aqueous medium, combined with approximately the same amounts of casein and borax, glycerin and a preservative.

9. A printing ink composition for use in intaglio printing comprising an aqueous medium, combined with casein and borax in approximately the same proportions, and preservatives.

10. An intaglio printing ink vehicle comprising an aqueous medium combined with casein and borax in substantially the same amounts and carbolic acid.

11. An intaglio printing ink vehicle comprising an aqueous medium combined with casein and borax in substantially the same amount, carbolic acid and oil of citronella.

12. A printing ink composition for use in intaglio printing, comprising skim milk combined with casein and borax in approximately the same proportions and preservatives.

In testimony whereof I affix my signature.

GEORGE D. KNIGHT. 

